Dew point indicator



May 15, 1945.

J. J. TURlN DEW POINT INDICATOR Filed. April 14, 1944 FI Z FIG. 1

ZSmaentor 'ZZZM' I (Ittor leg novel and my invention,

2-2 of Fig. 1.

' outermost disc chart I! is an arm 2d not touch the been obtained the needle end of the that the striker 24 bar will be m of moisture thereon from Patented May 15, 1945 UNITED STATES, PATENT; orrlcs John J. Turin, Ottawa Hills, Ohio,

Surface Combustion Corporation, Toledo,

a corporation of Ohio Application April 14, 1944, Serial No. 531,104

3 Claims. (cue-1'1) This invention relates to an, instrument for automatically ascertaining the dew point of a moisture-containing gas and-has for its object to provide an improved instrument of this typ For a consideration of what I believe to be attention is directed to the following specification and the claims appended thereto.

In the accompanying drawing,

Fig. 1 is a diagrammatic view of a dew point indicating apparatus embodying the presentinvention, and

Fig. 2 is a diagrammatic sectional view on line The gas whose dew p nt is to be ascertained is caused to flow through a testing chamber l0 by way of inlet and outlet pipes II and I2. Openly exposed to the gas in this chamber is a reflecting surface is which will ordinarily consist of a metal button ll mounted in'a wall l5 of the chamber.

ldindicates a recording meter which includes a chart disc ll rotated in the usual manner by a chart-driving shaft It. The circles on this chart indicate temperatures. Thus the innermost circle may indicate, say, -20 F. and the circle may indicate, say, 60 F. Mounted for rocking movement in front of the having at its free end which normally does chart ii. The position of this arm is controlled by the temperature of the reflecting button M through any preferred instrumentalities but which will usually comprise a thermocouple 22 at said button, it being undera punch pin or needle 2! stood that the needle ami is mounted on a rock shaft 23 whose turning instrumentalities.

As soon as the dew point of the said gas has v arm 20 is deflected towards the chart disc by means including a striker bar 24 to cause the needle 2| to is controlledby the said touch the chart to prick the same or to leave an ink spot thereon as may be preferred.

The means for operating the striker bar 24 is controlled by a plifier 21, the general arrangement being such operated to strike the needlearm 20 at the instant that any condensation of. moisture on the reflecting surface l3 disappears therefrom following a previous chilling of .said surface to cause a condensation said gas, it being un- Letters Patent is:

to cause periodic depositions of assignor to Ohio,

by light reflected from said surface. limiting or receiving tube of the photoelectric cell is indicated at 28 and the source of light at 29.

The reflecting surface is is periodically chilled moisture thereon from the gas in the chamber Hi to obtain periodic readings or indications of the dew point of said gas. This chilling of said surface i3 is readily effected by liberating compressed carbon dioxide in an expansion chamber 30 to which-the back side of the said surface is openly exposed. A periodically operated expansion valve is indicated at 3|. A'pi'pe 32 leads to this valve from a bottle 33 of compressed carbon dioxide and a pipe 3% leads into the expansion chamber at from said valve. The periodic opening and closing of the valve 8| is controlled by a timing mechanism 35 which controls the operation of an electric motor 36 which turns a shaft 8? having thereon a cam 38 which operates against a valve stem 39 for temporarily opening a ball valve fill in the flow passage between the pipes 32 and as. The timing mechanism is shown as comprising a mercury switch 49 which is tripped by a cam 82 on the shaft 31. Y a

The apparatus has been designed primarily for ascertaining the dew point of atmospheres used in the heat treatment of metals but, of course, is not limited in its application to such use.

Whatl claim as new and desire to secure by 1. In apparatus for ascertaining the dew point of a moisture-containing gas, the combination which comprises a reflecting surface openly exposed to said gas, 'a movable element, means for changing the position of said element in accordance with changes in temperature of said surface, means for momentarily chilling said surface to cause momentary condensation thereon of moisture in said gas, a source of light to which comprises an electrical device 25 whose operation photoelectric cell 26" through suitable instrumentalities including a current amcontrolled by said saidsurface is exposed, means for changing light variations from said surface caused by the said condensation into electrical variations, and means electrical variations for imparting to said movable element an eflect which will indicate that a place.

2. In apparatus for ascertaining'the dew point of a moisture-containing gas, the combination which comprises a reflectingsurface openly exposed to said gas, a movable element, means for changing the position of said element in accordance with temperature changes of saidsurface,

light variation has taken means for periodically momentarily chilling said surface'to cause periodic momentary condensation thereon of moisture in said gas, a source of light to which'said surface is exposed, means for changing light variations from said surface caused by the said condensation into electrical variations, and means controlled by said variations for momentarily imparting to said movable element an eflect which will indicate that a light variation has taken place.

3. In apparatus for ascertaining the dew point of a moisture-containing gas, the combination which comprises a reflecting surface openly exposed to said gas, a movable element, means for changing the position of said element in accordplace.

JOHN J. TURIN. 

